Significant efforts are currently underway to develop in-vehicle driver information systems which will allow a driver to efficiently plan and execute his or her travel routes. In addition to providing for the preplanning of travel routes, efforts are being made to develop systems which will account for changing road conditions, such as accidents and other road obstacles. One approach has been to broadcast traffic information to individual vehicles. Associated in-vehicle display and navigation systems display the received information and locate the driver on a map. Other approaches used in in-vehicle driver information systems have included navigation systems based on dead reckoning and satellite information.
The development of driver information systems having route scheduling and planning functions hereto have been limited by the inability of systems designers to capture and organize the large amounts of data associated with roadmaps. It is through the use of these roadmaps that the designers can develop "intelligent driver" technologies providing integrated navigation, route planning, and driver information at a reasonable cost in both commercial and private applications. Most significantly, prior art systems have been unable to provide scheduling functions such that multiple stop trips can be optimized as to time and distance. Drivers would benefit by an in-vehicle information system providing route planning and replanning capabilities through the ability to select the most convenient route and the ability to easily travel to unfamiliar destinations. Commercial delivery companies would benefit from better route scheduling and the consequent reduction in travel time and driver costs.
Thus, the need has arisen for an in-vehicle driver information system having the capability to efficiently plan and schedule travel routes, including multiple stop routes, based on a roadmap database using minimal memory resource. Further, the system should allow for the replanning and rescheduling of the travel routes based on changing road conditions, such as the occurrence of accidents.